As the volume of data generated by computing devices increases, the importance of memory space rises. Over the past several years, increases in demand for memory has caused a parallel increase in the capacity of mass memory storage devices. Conventionally, these mass memory storage devices comprise rotating mass storage devices such as disk drives. Although great strides have been made in disk drive design in terms of capacity and speed, the versatility of conventional disk drives may be limited.
A first limitation is that disk drive technology could soon reach a limit imposed by the superparamagnetic effect (SPE). SPE is a physical phenomenon in which the energy that holds the magnetic spin in the atoms forming each bit becomes susceptible to ambient thermal energy and, therefore, is subject to random flipping that corrupts the data that the atoms represent. Unfortunately, the miniaturization currently popular in disk drive manufacture may amplify the SPE problem.
A second limitation of disk drives relates to speed. Because disk drives require moving parts, the speed at which data can be stored on or accessed from the drive may be limited by the speed with which the various mechanical parts of the drive can move. To increase this speed, manufacturers have continually increased the speeds at which the internal disks of the drives rotate. However, along with this increased angular velocity comes increased air turbulence and vibration that can cause misregistration of the disk tracks. In addition, to achieve high capacity and high speed, disk drives must be very precise in operation.
Typically, disk drives comprise one or more disks and a plurality of read-write heads that record and retrieve data from circumferential tracks formed in the disks. The heads are normally moved with servomechanical actuator arms. To properly perform read/write operations, the heads must be positioned in very close proximity to the disks, the separation between the heads and the disks typically measuring only fractions of microinches. This level of precision often results in a very fragile mechanism that can be easily damaged by moderate to large vibrations. Such susceptibility may be particularly disadvantageous for portable computing devices that are often bumped and/or jolted through normal use.
In addition to fragility, disk drives may further present the disadvantage of requiring relatively large amounts of power to operate. This again relates to the fact that disk drives have moving parts that require electrical power. Although not a major concern for plug-in devices such as desktop computers, this power consumption may be problematic for portable devices.